Reduced salt precipitation in carbohydrate containing binder compositions

ABSTRACT

Aqueous binder compositions with reduced rates of salt precipitation are described. The compositions may include a carbohydrate and a sequestrant for sequestering one or more multivalent ions (e.g., Ca 2+ , Mg 2+ , Ba 2+ , Al 3+ , Fe 2+ , Fe 3+ , etc.). The sequestrant reduces a precipitation rate for the multivalent ions from the aqueous binder composition. Methods of reducing salt precipitation from a binder composition are also described. The methods may include the steps of providing an aqueous binder solution having one or more carbohydrates. They may also include adding a sequestrant for one or more multivalent ions to the aqueous binder solution. The sequestrant reduces a precipitation rate for the multivalent ions from the binder composition.

BACKGROUND

Manufacturers continue to develop replacement binder formulations toreplace the traditional phenol-formaldehyde and urea-formaldehydebinders that have been used for decades. Formaldehyde is considered aprobable human carcinogen, as well as an irritant and allergen, and itsuse is increasingly restricted in building products, textiles,upholstery, and other materials. In response, formaldehyde-free bindersystems are being developed and commercialized.

The first generation of replacement binder systems includedpolycarboxylic acid formulations that polymerized polycarboxylic acidsand alcohols. The polymerization reaction involved the esterification ofthe carboxylic acid groups on the polycarboxylic acids and the hydroxylgroups on the alcohols, which generated environmentally benign water asthe main polymerization byproduct. However, the high concentrations ofpolycarboxylic acids in these binder formulations make them very acidicand create corrosion problems for the manufacturing equipment used tomake fiberglass insulation and fiber-reinforced composites.

The first generation of replacement binders also tend to rely heavily onnon-renewable, petroleum-based starting compounds. Increasing worldwidedemand for fossil fuels has driven up the costs of these materials andcreated both economic and environment concerns about the sustainabilityof these binder systems. Thus, manufacturers have been developing a newgeneration of replacement binder formulations that reduce or eliminatepetroleum-derived starting materials.

One promising new class of binder systems rely on carbohydrates as asustainable, environmentally benign replacement for the petroleum-basedstarting compounds. Carbohydrate-based binder systems typicallypolymerize reducing sugar carbohydrates with a crosslinking compound toproduce an effective binder for fiberglass insulation and otherproducts. The polymerization process converts the water solublecarbohydrates into water insoluble polymers with good moistureresistance and aging characteristics.

Carbohydrate binder formulations normally start as aqueous solutionsthat are saturated with the starting carbohydrates. The formulations mayalso include polymerization catalysts that are often metallic ammoniumsalts of simple inorganic acids. Unfortunately, the high concentrationsof carbohydrates in the aqueous binder solution substantially reduce itscapacity for dissolving these salts. The poor solubility of the catalystis compounded by the ions that commonly contaminate theindustrial/municipal sources of water used in the binder solution.Between the multivalent ions that naturally contaminate the water sourceand the additional ions added by the catalyst, the binder solution oftenbecomes oversaturated and precipitate out a quantity of the salts. Asthese salt precipitates build up in the equipment that transports thebinder solution, they can cause frequent and costly maintenanceshutdowns.

One way to reduce these shutdowns is to decontaminate the supply ofwater used to make the binder formulations. These decontaminationtechniques include running the water through ion exchange columns thatreplace a portion of the multivalent ions with monovalent ions such assodium (Na⁺) or potassium (K⁺) ions. This process is sometimes referredto colloquially as water softening, and the ion exchange equipment as awater softener. Unfortunately, the ion exchange columns need frequentand costly recharging to reduce the multivalent ion concentrations tothe levels needed, which has a significant effect on maintenanceshutdowns and makes this approach impractical for most manufacturingapplications. In addition, the addition of extra sodium ions can have anadverse effect on cure rate and water resistance in the cured binder.Thus, there remains a need to address the salt precipitation problemswith carbohydrate binder solutions, and this and other problemsaddressed in the present application.

BRIEF SUMMARY

Binder formulations are described that include one or more sequestrantsfor multivalent ions that prevent the precipitation of the sequesteredions from the binder solution. These sequestrants can suppress saltprecipitation rates from aqueous carbohydrate-containing bindersolutions that have a low capacity for the dissolved ions (i.e., lowsolubility). However, it should be appreciated that the sequestrants canwork in other aqueous binder systems with a low capacity for these ions,even if the cause of the capacity problem is not due to carbohydrateloading. Thus, embodiments of the present binder formulations can extendto binders with few or no carbohydrates.

Embodiments of the invention include aqueous binder compositions. Thecompositions may include a carbohydrate and a sequestrant forsequestering one or more multivalent ions (e.g., Ca²⁺, Mg²⁺, Ba²⁺, Al³⁺,Fe²⁺, Fe³⁺, etc.). The sequestrant reduces a precipitation rate for themultivalent ions from the aqueous binder composition.

Embodiments of the invention further include methods of reducing saltprecipitation from a binder composition. The methods may include thesteps of providing an aqueous binder solution having one or morecarbohydrates. The methods may also include adding a sequestrant for oneor more multivalent ions to the aqueous binder solution. The sequestrantreduces or eliminates a precipitation rate for the multivalent ions fromthe binder composition.

Embodiments of the invention still further include methods of making afiber-containing composite. The method may include the steps ofproviding woven or non-woven fibers, and applying a binder compositionto the woven or non-woven fibers. The binder composition may include acarbohydrate, a crosslinking agent, and a sequestrant for one or moremultivalent ions. The application of the binder composition to thefibers makes a fiber-binder amalgam that may be cured and formed intothe fiber-containing composite.

Additional embodiments and features are set forth in part in thedescription that follows, and in part will become apparent to thoseskilled in the art upon examination of the specification or may belearned by the practice of the invention. The features and advantages ofthe invention may be realized and attained by means of theinstrumentalities, combinations, and methods described in thespecification.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the presentinvention may be realized by reference to the remaining portions of thespecification and the drawings wherein like reference numerals are usedthroughout the several drawings to refer to similar components. In someinstances, a sublabel is associated with a reference numeral and followsa hyphen to denote one of multiple similar components. When reference ismade to a reference numeral without specification to an existingsublabel, it is intended to refer to all such multiple similarcomponents.

FIG. 1 shows a simplified schematic with selected steps in a method ofmaking a fiber composite using the present binder formulations;

FIG. 2 shows a simplified schematic with selected steps in a method ofmaking a fiber composite using the present binder formulations;

FIG. 3 depicts a simplified schematic of an exemplary fabrication systemfor making the fiber-containing composites according to embodiments ofthe invention; and

FIG. 4A-C illustrate a simplified schematics of exemplary compositematerials according to embodiments of the invention.

DETAILED DESCRIPTION

The present binder formulations include a sequestrant in an aqueousbinder solution. The formulations may include a variety of bindersystems with a low salt capacity (i.e., a low solubility for multivalentcation salts) that employ the sequestrant to reduce or eliminate theprecipitation of the salts as the binder solution is being prepared,applied and/or cured. Exemplary binder systems may include polymericbinder reactants such as polycarboxylic acids, polyhydric alcohols,carbohydrates, amines, and/or crosslinking agents, among others. Asnoted above, frequent salt precipitation was noted in binderformulations containing carbohydrate reactants (e.g., reducing sugars)that lower the saturation concentration of multivalent salts in thesolution. Reformulating these binder systems to include at least one ofthe present sequestrants significantly reduces precipitation of themultivalent salts.

Exemplary sequestrants include polycarboxylic acid compounds that havetwo or more carboxylic acid groups, three or more carboxylic acidgroups, four or more carboxylic acid groups, five or more carboxylicacid groups, etc. For example, ethylenediaminetetraacetic acid (EDTA)and citric acid, having the structural formulas shown below, may besequestrants:

Other amino-carboxylic acids include ethylenediaminetetrasuccinic acid,tetraitaconicacid and/or their salts with ammonia, amine, and/or alkalimetal ions such as Na⁺ and K⁺.

Exemplary sequestrants also include polyphosphonic acid andpolyphosphoric acid compounds that have two or more phosphonic acidgroups (—PO(OH)₂), three or more phosphonic acid groups, four or morephosphonic acid groups, five or more phosphonic acid groups, etc. Forexample, ethylenediaminetetramethylenephosphonic acid (EDTMP), havingthe structural formula shown below, may be a sequestrant:

Polyphosphoric acids may have the following structure, having thestructural formula shown below, may also be a sequestrant:

The present sequestrants may still further include polyacrylic acidcompounds that have two or more carboxylic acid groups or salts thereof.As noted below, the polyacrylic acid compounds may be added in lowconcentrations to the binder solution (e.g., about 1 wt. % or less)where the function primarily as a sequestrant. Alternatively, they maybe added in higher concentrations where they can make a significationcontribution to the physical and mechanical properties of the binder aswell as act as a sequestrant.

The present sequestrants show efficacy at sequestering multivalentcations such as alkali earth metal cations, and transition metalcations, among other multivalent cations. Examples of these multivalentcations include calcium ions (Ca²⁺), magnesium ions (Mg²⁺), barium ions(Ba²⁺), aluminum ions (Al³⁺) and iron ions (Fe²⁺, Fe³⁺), among others.The sequestered ions remain dissolved in the aqueous binder solutioneven beyond the saturation limit for an unsequestered solution.

The efficiency level of a sequestrant may be measured as the thresholdconcentration level (e.g., wt. %) of the sequestrant required to preventprecipitation of a standardized binder solution at temperatures used incomposite manufacturing processes. The present sequestrants may haveefficacy levels ranging from about 0.1 wt. % to about 2 wt. % of thebinder solution. For example, the sequestrant may have an efficacy levelof about 0.5 wt. % or less, about 0.4 wt. % or less, about 0.3 wt. % orless, about 0.2 wt. % or less, etc.

Exemplary Sequestrant-Containing Binder Systems

The exemplary binder formulations may include the sequestrants combinedwith renewable materials such as carbohydrates (e.g., dextrose,fructose, starches, celluloses, hemicellulases. etc.), and/or proteins(e.g., soy flour), among other renewable materials. When the binderformulation includes reducing sugar carbohydrates, they may also includeone or more nitrogen-containing compounds. The nitrogen containingcompounds may include ammonia, ammonium salts, amines, amides, aminoacids, imides, and reaction products of urea and aldehyde reactants,among other compounds. The binder formulations may further includeadhesion prompters, oxygen scavengers, solvents, emulsifiers, pigments,organic and/or inorganic fillers, flame retardants, anti-migration aids,coalescent aids, wetting agents, biocides, plasticizers, organosilanes,anti-foaming agents, colorants, waxes, suspending agents, anti-oxidants,and secondary crosslinkers, among other components.

The nitrogen-containing compounds may include a variety of compoundsthat can distinguish a class of carbohydrate binders. One class ofbinders uses an amino-amide as the nitrogen containing compound, whichitself is a reaction product of an amine with a saturated or unsaturatedreactant. Another class uses nitrogen-containing compounds that arereaction products of urea compounds and aldehyde-containing compounds.Some exemplary classes of carbohydrate-and-nitrogen-containing bindersare described in more detail below.

I. Carbohydrate-and-Nitrogen Containing Binders

1. Carbohydrate/Amino-Amide Binder Formulations

The nitrogen-containing compounds may include amines capable ofundergoing conjugate addition with a saturated or unsaturated reactantto form an amino-amide. The amino-amide then reacts during curing withthe carbohydrate to form a polyimide. The amino-amide addition productsmay be formed by mixing the amine and saturated or unsaturated reactantin an aqueous medium at room temperature. The resulting additionproducts are either water-soluble, water-dispersible, or are present asan emulsion. In some binder formulations, the formation of theamino-amide from the reaction of the amine precursor with the saturatedor unsaturated reactant may occur before the introduction of thecarbohydrate, while other formulations mix all three precursors (i.e.,the amine, saturated or unsaturated reactant, and carbohydrate) beforethe amino-amide is formed.

Each amine may have two or more primary and/or secondary amine groups toreact and crosslink two or more carbohydrate molecules. The amines mayinclude aliphatic, cycloaliphatic and aromatic amines. They may belinear or branched, and have additional functionalities and linkagessuch as alcohols, thiols, esters, amides, acids, and ethers, amongothers. Exemplary amines may include 1,2-diethylamine,1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine,1,6-hexanediamine, α,α′-diaminoxylene, diethylenetriamine,triethylenetetramine, tetraethylenepentamine, as well as combinations oftwo or more of these amines. Natural and synthetic amino acids such aslysine, anginine, hestidine, etc., may also be used.

The curable amino-amide is formed through the selection of anunsaturated or saturated reactant that is an anhydride, carboxylic acid,ester, and salts and mixtures of such reactants. These unsaturatedreactants may include maleic acid, fumaric acid, maleic anhydride, mono-and di-esters of maleic acid and fumaric acid, and salts and mixtures ofthese. Ammonium salts of the unsaturated acids of their monoestersconveniently can be utilized. Saturated reactants may include, withoutlimitation, succinic anhydride, succinic acid, mono and diesters ofsuccinic acid, glutaric acid and anhydride, phthalic acid and anhydride,tetrahydro phthalic acid and anhydride, mono and diesters of acidanhydrides and salts of the acids, and their mono esters.

In some formulations, the amino-amide product may be oligomerized beforereacting with the carbohydrate. This oligomerization may be facilitatedby heating the amino-amide solution until the amino-amide is dimerized,trimerized, tetramerized, etc., into the amino-amide oligomer. Theheating conditions may include raising the temperature of theamino-amide solution to, for example, 120° C. to 150° C. for a time ofup to 5 hours. In some instances, the oligomerized amino-amide productforms a stronger, more rigid cured binder product than then amino-amidemonomer.

Then during the binder curing step, the majority of the carbohydratereacts with the amino-amide intermediate, which contains an amic acidfunctional group, (i.e., an amide linkage in the vicinity of acarboxylic acid). An amic acid functional group is typically morereactive than a simple carboxylic acid. The amount of carbohydrate addedis generally such that the molar ratio of carboxylic acid in theamino-amide to carbonyl or ketone in the carbohydrate is from 1:5 to50:1, for example a ratio of 1:20 to 20:1, or a ratio of 1:10 to 10:1.Additional details about carbohydrate/amino-amide binder formulationsare described in co-assigned U.S. patent application Ser. No. 12/539,263to Shooshtari et al, filed Aug. 11, 2009, and titled “Curable FiberglassBinder,” the entire contents of which are herein incorporated byreference for all purposes.

2. Carbohydrate/Urea Derivative Binder Formulations

The nitrogen-containing compounds may include urea derivative reactionproducts of urea (i.e., H₂N—CO—NH₂), and/or substituted ureas, withdiformaldehyde compounds such as glyoxal. One specific class of theseurea derivatives include imidazolidine compounds such as4,5-dihydroxyimidazolidin-2-one, which has the chemical structure:

More specifically, the urea compound may be a substituted ourunsubstituted urea having the formula:

where R₁, R₂, R₃, and R₄ are independently chosen from a hydrogen moiety(H), an alkyl group, an aromatic group, an alcohol group, an aldehydegroup, a ketone group, a carboxylic acid group, and an alkoxy group.Exemplary alkyl groups include straight-chained, branched, or cyclichydrocarbons of varying size (e.g., C₁-C₁₂, C₁-C₈, C₁-C₄, etc.).Exemplary aromatic (i.e., aryl) groups include substituted orunsubstituted phenyl moieties, among other aromatic constituents.Exemplary alcohol groups include —ROH, where R may be a substituted orunsubstituted, saturated or unsaturated, branched or unbranched, cyclicor acyclic, organic moiety. For example, R may be —(CH2)_(n)—, where nmay be 1 to 12. Exemplary alcohols may also include polyols having twoor more hydroxyl groups (—OH) in alcohol group. Exemplary aldehydegroups include —RC(═O)H, where R may be a monovalent functional group(e.g., a single bond), or a substituted or unsubstituted, saturated orunsaturated, branched or unbranched, cyclic or acyclic, organic moiety,such as —(CH2)_(n)—, where n may be 1 to 12. Exemplary ketone groups mayinclude —RC(═O)R′ where R and R′ can be variety of carbon containingconstituents. Exemplary carboxylic acid groups may include —R—COOH,where R may be a monovalent functional group, such as a single bond, ora variety of carbon-containing constituents. Exemplary alkoxy groupsinclude —OR_(x), where R_(x) is an alkyl group.

The aldehyde-containing compound may contain one or more aldehydefunctional groups. Exemplary aldehyde-containing compounds includeacetaldehyde, propanaldehyde, butyraldehyde, acrolein, furfural,glyoxal, gluteraldehyde, and polyfurfural among others. Exemplaryaldehyde-containing compounds may also include substituted glyoxalcompounds having the formula:

where R₅ and R₆ may be independently hydrogen (H), an alkyl group, anaromatic group, an alcohol group, an aldehyde group, a ketone group, acarboxylic acid group, and an alkoxy group, among other groups.

The reaction products of the urea compound and the aldehyde-containingcompound may include an imidazolidine compound having the formula:

where R₇, R₈, R₉, and R₁₀ are independently, —H, —OH, —NH₂, an alkylgroup, an aromatic group, an alcohol group, an aldehyde group, a ketonegroup, a carboxylic acid group, and an alkoxy group. In one specificexample of the reaction between urea and glyoxal, the reaction productmay be 4,5-dihydroxyimidazolidin-2-one.

The pH of the present binder compositions may vary depending upon thetypes and relative concentrations of the components used. Typically thepH of the present binder compositions are slightly acidic to alkalinewith a pH range of about 6 to 8 (e.g., 6.5 to 7.5). The bindercompositions have a pH that creates relatively little or no acid-basedcorrosion of metal fabrication equipment.

The reaction product of the urea derivative nitrogen-containing compoundacts as a crosslinking agent for the carbohydrate. During a curingstage, the urea derivative can bond to two or more carbohydrates (eitherpolymerized or unpolymerized) to form a crosslinked, polymeric curedbinder.

The molar ratio of the (1) crosslinking reaction product of the ureacompound and the aldehyde-containing compound to (2) the carbohydrategenerally ranges from 1:2 to 1:50. Exemplary ratios of crosslinkingagent to carbohydrate include a range from 1:4 to 1:10. Additionaldetails about carbohydrate/urea derivative binder formulations aredescribed in co-assigned U.S. patent application Ser. No. 13/490,638 toShooshtari et al, filed Jun. 7, 2012, and titled “Formaldehyde-FreeBinder Compositions with Urea-Formaldehyde Reaction Products,” theentire contents of which are herein incorporated by reference for allpurposes.

3. Carbohydrate/Nitrogen-Containing Salt Binder Formulations

i. Salts of Inorganic Acids with Amines

In additional carbohydrate binder formulations, the nitrogen-containingcompounds may include a nitrogen-containing salt. For example, thenitrogen-containing compound may include the salt product of thecombination of an inorganic acid and an amine (e.g., an amine-acidsalt). Exemplary inorganic acids may include a phosphorous-containingacid such as phosphoric acid, pyrophosphoric acid, phosphorous acid, andphosphine, among others. Exemplary inorganic acids may also includeoxygenated inorganic acids such as sulfuric acid, sulfurous acid, nitricacid, boric acid, hypochloric acid, chlorate acid, among others. Theymay also include non-oxygenated inorganic acids such as hydrochloricacid and hydrogen sulfide, among others.

Exemplary amines may include polyamines (e.g., diamines, triamines,etc.) having at least one primary amine group. For example, the aminesmay include ethylene diamine, 1,3-propanediamine, 1,4-butanediamine,1,5-pentanediamine, 1,6-hexanediamine, α,α′-diaminoxylene,diethylenetriamine, triethylenetetramine, tetraethylenepentamine, aswell as combinations of two or more of these amines.

When the amine-acid salt reacts with the carbohydrate under bindercuring conditions the binder is formed. Exemplary binder systems includethe combination of an amine-acid salt of 1,6-hexanediamine andphosphoric acid with the carbohydrate dextrose (HPD), the combination ofan amine-acid salt formed from the combination of ethylene diamine andphosphoric acid with dextrose (EPD). Additional details about theseamine-acid salt and carbohydrate binder formulations are described inco-assigned U.S. patent application Ser. No. 12/539,211, filed Aug. 11,2009 to Shooshtari, the entire contents of which are herein incorporatedby reference for all purposes.

ii. Salts of Inorganic Acids with Amines and Organic Species

Some carbohydrate/amine-acid salt binder formulations further includesome combination of an organic acid, organic anhydride, and/or analkanol amine. Exemplary organic acids may include polycarboxylic acidsuch as citric acid and or maleic acid. Exemplary organic anhydrides mayinclude maleic anhydride, phthalic anhydride, methylphthalic anhydride,glutaric anhydride, tetrahydrophthalic anhydride, perhydrophthalicanhydride, itaconic anhydride, succinic anhydride, and trimelliticanhydride, among other anhydrides.

Exemplary alkanol amines may have the formula:

where R₁, R₂, and R₃ are independently chosen from, a hydrogen, a C₁₋₁₀alkyl group, an aromatic group, and a C₁₋₁₀ hydroxy alkyl group, andwherein at least one of R₁, R₂, and R₃ is a hydroxyl alkyl group.

Specific examples of alkanol amines may include methanol amines such asmono-, di-, and tri-, methanol amine; ethanol amines such as monoethanolamine (MEA), diethanol amine (DEA), and triethanol amine (TEA);isopropanol amines such as mono-, di-, and tri-, isopropanol amine;methyldiethanol amine; ethyldiethanol amine; propyldiethanol amine;isopropyldiethanol amine; and n-butyldiethanol amine, among others.

Exemplary carbohydrate binder formulations may include the combinationof a carbohydrate, amine-acid salt, and organic acid. These includebinder formulations of dextrose, ethylene diamine phosphate, and citricor maleic acid. Additional details about these carbohydrate/amine-acidsalt/organic acid binder formulations are described in co-assigned U.S.patent application Ser. No. 13/478,765, filed May 23, 2012 to Shooshtariet al, the entire contents of which are herein incorporated by referencefor all purposes.

Exemplary carbohydrate binder formulations may also include thecombination of a carbohydrate, amine-acid salt, organic anhydride, andalkanol amine. This include binder formulations of the reaction productsof monoethanol amine (“E”) and maleic anhydride (“M”) combined withethylenediamine phosphate (“EP”) and dextrose (“D”) to make bindercompositions referred to as EMEPDs. In still other exemplary binderformulations, the amine-acid salt may be eliminated. This includesformulations of the reaction products of monoethanol amine (“E”) andmaleic anhydride (“M”) with the carbohydrate dextrose to make bindercompositions referred to as EMDs. Additional details about thesecarbohydrate/amine-acid salt/anhydride-alkanol amine binder formulationsare described in co-assigned U.S. patent application Ser. No.13/559,769, filed Jul. 27, 2012 to Shooshtari et al, the entire contentsof which are herein incorporated by reference for all purposes.

Exemplary binder formulations may include additional compounds combinedwith the reducing sugar, organic acid, and amine salt of an inorganicacid. For example, urea may also be included with the other bindercomponents. Exemplary, urea-containing binder compositions may includeethylene diamine phosphate (“EP”), citric acid (“C”), urea (“U”), anddextrose (“D”) combined to make a binder composition referred to asEPCUD. Exemplary molar ratios of these components may includeEthylenediamine:Phosphoric Acid:Citric Acid:Urea:Dextrose of1:1:0.5:1:6.

iii. Ammonium Salts of Carboxylic Acids

In still additional carbohydrate binder formulations, thenitrogen-containing compounds may include an ammonium salt of apolycarboxylic acid. Exemplary ammonium salts of polycarboxylic acidsmay be formed from the reaction of ammonia (NH₃) with the polycarboxylicacid to form the ammonium salt. It should be appreciated that othertypes of ammonium ions can function as the cation in theammonium-polycarboxylate salt, such as (NH₃R₁)⁺, (NH₂R₁R₂)⁺, and(NHR₁R₂R₃)⁺, where R₁, R₂, and R₃ are each independently chosen from analkyl, cycloalkyl, alkenyl, cycloalkenyl, heterocyclyl, aryl, andheteroaryl, among other organic groups.

Exemplary polycarboxylic acids may include dicarboxylic acids,tricarboxylic acids, etc. Dicarboxylic acids may include maleic acid,and tricarboxylic acids may include citric acid.

The binder formulations may include the combination of a carbohydrate(e.g., a reducing sugar) with the ammonium salt of the polycarboxylicacid. For example, the binder composition may include dextrose andtriammonium citrate.

4. Carbohydrate Blends with Latex and/or Solution Polymers

This group of carbohydrate binder compositions is distinguished by theinclusion of the components of a second binder in the formulation. Thesecond binder may be a latex binder and/or solution polymer with asignificantly higher viscosity than the carbohydrate binder composition.In some instances, the second binder may act as the sole thickeningagent in the carbohydrate binder composition, while in other instancesthe second binder may complement other thickening agents to get thecomposition to a target viscosity.

The second binder may include latex binders having a Brookfieldviscosity of about 100 cPs or more (spindle 18 operating at a speed of60 rpm) at 20° C. Exemplary second binders may include acrylic binders,among others. The second binder may be present up to about half theweight of the total binder composition (e.g., 1 to 50 wt. %; 1 to 20 wt.%; etc.).

II. Blends of Carbohydrate and Acrylic Acid Binders

The present binder compositions may also include blends ofcarbohydrate-containing binder compositions and polyacrylic acidcontaining binder compositions. For example, one of the above-describedcarbohydrate-and-nitrogen containing binder compositions may be combinedwith a polyacrylic acid binder to create a blended binder composition.The polyacrylic acid component may act as both a sequestrant and abinder, eliminating the need for an additional sequestrant in the bindercomposition.

Exemplary concentration ratios of the polyacrylic binder to thecarbohydrate binder may range from about 0.5:99.5 to about 50:50. Asmall ratio of the polyacrylic binder (e.g., about 2 wt. % or less) isused when the polyacrylic compound functions primarily as a sequestrant,while larger ratios increase the effect of the polyacrylic acid on thephysical and mechanical properties of the composite. For both low andhigh ratios, the polyacrylic acid may act as the exclusive sequestrantto slow or prevent the precipitation of multivalent salt compounds, ormay act in combination with one or more additional sequestrants tosequester the multivalent ions in the binder composition.

The polyacrylic binder compositions may also include crosslinkers,catalyst, and other compounds that facilitate the polymerization of thebinder. Exemplary crosslinking agents may include alkanol amines such astriethanol amine. Exemplary catalysts may include hypophosphitecompounds such as sodium hypophosphite (SHP).

III. Multivalent Salt Catalysts for Binder Systems

Many binder formulations, including many carbohydrate-and-nitrogencontaining binder formulations, include catalysts to increasepolymerization rates as the binder cures. These catalysts often includemetallic salts, including multivalent cation salts.

Exemplary binder catalysts may include alkaline catalysts and acidiccatalysts. The acidic catalysts may include Lewis acids (includinglatent acids and metallic salts), as well as protic acids, among othertypes of acid catalysts. Lewis acid catalysts may include a multivalentcation salt of a deprotonized anion such as a sulfate, sulfite, nitrate,nitrite, phosphate, halide, or oxyhalide anion, among other anions. Themultivalent cation may include in combination with one or more metalliccations such as aluminum, zinc, iron, copper, magnesium, tin, zirconium,and titanium. Exemplary Lewis acid catalysts include aluminum sulfate,ferric sulfate, aluminum chloride, ferric chloride, aluminum phosphate,ferric phosphate, and sodium hypophosphite (SHP), among others.Exemplary latent acids include acid salts such as ammonium sulfate,ammonium hydrogen sulfate, mono and dibasic ammonium phosphate, ammoniumchloride, and ammonium nitrate, among other latent acid catalysts.Exemplary metallic salts may include organo-titanates andorgano-zirconates (such as those commercially manufactured under thetradename Tyzor® by DuPont), organo-tin, and organo-aluminum salts,among other types of metallic salts. Exemplary protic acids includesulfuric acid, phosphoric acid, hydrochloric acid, nitric acid, sulfonicacid compounds (i.e., R—S(═O)₂—OH) such as p-toluenesulfonic acid andmethanesulfonic acid, and carboxylic acids, among other protic acids.Catalyst compositions may also include combinations of two or morecatalysts, for example the combination of ammonium sulfate anddiammonium phosphate.

Exemplary Methods of Making Fiber Composites

The present sequestrant-containing binder formulations may be used inmethods of making a variety of fiber composites. FIG. 1 shows aflowchart with selected steps in a method 100 of making a fibercomposite using the present binder formulations. The method 100 mayinclude providing a binder solution 102 that may include multivalent ioncontaining components, such as a polymerization catalyst. A multivalention sequestrant may be added to the binder solution 104 to reduce orprevent the precipitation of salts from the binder solution.

The sequestrant-containing binder solution may be added to fibers tomake a binder-fiber amalgam 106. The binder solution may be applied tothe fibers by a variety of techniques including spraying, spin-curtaincoating, curtain coating, and dipping-roll coating. The composition canbe applied to freshly-formed fibers, or to fibers that have been cooledand processed (e.g., cut, coated, sized, etc.). In method 100, thebinder solution is provided to the applicator as a premixed composition.Alternate techniques may be used, such as having separate components ofthe binder formulation supplied to the applicator in separate solutions.For example, separate binder and sequestrant solutions may be applieddirectly on the fibers.

The binder-fiber amalgam may be cured and the fiber-containing compositemay be formed 108. Techniques for curing the binder composition mayinclude exposing the composition applied to the fibers to an environmentconducive to curing. For example, the curable amalgam of fibers andbinder composition may be heated to a binder curing temperature.Exemplary binder curing temperatures may include a temperature rangefrom 100° C. to 250° C. The curing amalgam may be heated to the curingtemperature for a period of 1 minute to 100 minutes (e.g., 20 minutes).In some exemplary methods, additional agents like an anti-dusting agentmay be applied during or following the curing step 108.

Excess binder solution is often applied to the fibers during theapplication step, and at least a portion of this unused binder may berecaptured and optionally recycled back in to the binder solution 110applied to the fibers. It should be noted that the exposure of theunused binder solution to the fibers may cause the introduction of moremultivalent ions from the fibers. The additional ions leached from thefibers may be sequestered with the sequestrant that is added to thebinder solution.

Referring now to FIG. 2, another method 200 of using the present binderformulations to make fiber composites is illustrated. The method 200 mayinclude the step of providing a fiber mat 202. When the fiber compositeis fiberglass insulation, the fiber mat is normally a non-woven mat ofglass fibers. Other fiber composites may have additional types of fiberssuch as carbon fibers, inorganic fibers, mineral fibers, and organicpolymer fibers, among other types of fibers.

In method 200, the binder solution may be added to the fiber mat 204,and a sequestrant solution may be added to the fiber mat 206. The twosolutions may be kept separate until they are added to the mat and maybe supplied is separate steams to the mat. When they are applied asseparate streams, they may be applied simultaneously or sequentially tothe mat. For example, the sequestrant solution may be applied before,concurrently, or after the binder solution is applied to the mat.

The application of the binder and sequestrant solutions to the fiber matform a binder-fiber amalgam that may be cured into the fiber-containingcomposite 208. Similar to method 100, unused binder and sequestrantsolutions may be captured and the unused binder/sequestrant mixture maybe recycled into the binder solution.

Exemplary Fiber Composite Fabrication Systems

The sequestrant-containing binder formulations may be used to make avariety of fiber-reinforced composites, including fiberglass insulation,glass fiber mats for roofing shingles, and fiberglass facers, amongother products. FIG. 3 shows a simplified schematic of an exemplaryfabrication system 300 that may be used to make fiber-containingcomposites. The system 300 includes fiber supply unit 302 that suppliesthe fibers for the composite. The fiber supply unit 302 may be filledwith pre-made fibers, or may include equipment for making the fibersfrom starting materials such as molten glass. The fiber supply unit 302deposits the fibers 304 onto a porous conveyor belt 306 that transportsthe fibers under the binder supply unit 308.

The binder supply unit 308 contains a liquid uncured binder composition310, that is deposited onto the fibers 304. In the embodiment shown, thebinder composition 310 is spray coated onto the fibers 304 with spraynozzles 312, however, other application techniques (e.g., curtaincoating, dip coating, etc.) may be used in addition to (or in lieu of)the spray coating technique illustrated by nozzles 312.

The binder composition 310 applied on fibers 304 forms a fiber andbinder amalgam on the top surface of the conveyor belt 306. The belt 306may be perforated and/or porous to allow excess binder composition 310to pass through the belt 306 to a collection unit (not shown) below. Thecollection unit may include filters and circulation pumps to recycle atleast a portion of the excess binder back to the binder supply unit 308.

The conveyor belt 306 transports the amalgam to an oven 314 where it isheated to a curing temperature and the binder composition starts tocure. The temperature of the oven 314 and the speed of the conveyor belt306 can be adjusted to control the curing time and temperature of theamalgam. In some instances, process conditions may set to completelycure the amalgam into the fiber-containing composite. In additionalinstances, process conditions may be set to partially cure the amalgaminto a B-staged composite.

The amalgam may also be compressed prior to or during the curing stage.System 300 shows an amalgam being compressed by passing under a plate316 that tapers downward to decrease the vertical space available to thecuring amalgam. The amalgam emerges from under the plate 316 in acompressed state and has less thickness than when it first made contactwith the plate. The taper angle formed between the plate 316 andconveyor belt 306 can be adjusted to adjust the level of compressionplaced on the amalgam. The partially or fully cured composite thatemerges from under plate 316 can be used for a variety of applications,including construction materials such as pipe, duct, and/or wallinsulation, among other applications.

Exemplary Fiber Composites

FIG. 4A-C illustrate some of exemplary composite materials made with thepresent sequestrant-containing binder formulations. FIG. 4A is asimplified schematic of an exemplary fiber-containing batt material 402that may be used for building insulation. The material 402 may include abatt 403 of non-woven fibers held together by the binder. The fibers maybe glass fibers used to make fiberglass insulation (e.g, low-density orhigh-density fiberglass insulation), or a blend of two or more types offibers, such as a blend of glass fibers and organic polymer fibers,among other types of fibers. In some examples, a facer 404 may beattached to one or more surfaces of the batt 403.

FIG. 4B is a simplified schematic of an exemplary fiber-containingcomposite board 406 that may be used as an insulation board, duct board,elevated temperature board, etc. The fibers in board 406 may includeglass fibers, organic polymer fibers, carbon fibers, mineral fibers,metal fibers, among other types of fibers, and blends of two or moretypes of fibers.

FIG. 4C is a simplified schematic of an exemplary fiber-containingflexible insulation material 408 that may be used as a wrap and/or linerfor ducts, pipes, tanks, equipment, etc. The fiber-containing flexibleinsulation material 408 may include a facer 410 attached to one or moresurfaces of the fiber material 412. Exemplary materials for the facer410 may include fire-resistant foil-scrim-kraft facing.

Specific examples of fiber-containing composites that use the presentbinder compositions include low-density fiberglass insulation (e.g.,less than about 0.5 lbs/ft³) and high-density fiberglass insulation.

EXAMPLES

The efficiency levels of some exemplary sequestrants were measured bydetermining threshold concentrations of the sequestrants needed toprevent formation of precipitates in a binder formulation prepared asfollows: Mineralized water containing 10,000 ppm calcium, magnesium andsodium ions, 5000 ppm of iron ions, and 500 ppm of aluminum ions, wasadded to a binder solution in a water:binder weight ratio of 80:20. Thebinder solution included dextrose mixed with a urea-glyoxal crosslinkingagent and 2.5 wt. % ammonium sulfate, 2.5 wt. % diammonium phosphate,and 2 wt. % amino-silane (A-1100).

Sequestrants were added to the above-described binder formulation andthreshold sequestrant concentrations were measured below which a saltprecipitate would appear. Table 1 shows the threshold precipitateconcentrations in wt. % of the added sequestrant in the binderformulation:

TABLE 1 Threshold Sequestrant Concentrations to Prevent SaltPrecipitation: Sequestrant Threshold Sequestrant Conc (wt. %) EDTA 0.2Citric Acid 1.0 Polyacrylic Acid 1.1-1.5 Polyphosphonic Acid 0.15Styrene Malic Anhydride (SMA) 1.2

As a control the mineralized water was replaced with deionized water andno precipitation was observed when the DI water and binder solution weremixed even in the absence of a sequestrant.

The results of Table 1 show that all the polycarboxylic acid andpolyphosphonic acid group sequestrants showed some level of efficiencypreventing the precipitation of salts from the mineral water and bindersolution combination. The highest efficiencies for this combination ofmultivalent ions were observed with EDTA and polyphosphonic acidsequestrants.

Having described several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of theinvention. Additionally, a number of well-known processes and elementshave not been described in order to avoid unnecessarily obscuring thepresent invention. Accordingly, the above description should not betaken as limiting the scope of the invention.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimits of that range is also specifically disclosed. Each smaller rangebetween any stated value or intervening value in a stated range and anyother stated or intervening value in that stated range is encompassed.The upper and lower limits of these smaller ranges may independently beincluded or excluded in the range, and each range where either, neitheror both limits are included in the smaller ranges is also encompassedwithin the invention, subject to any specifically excluded limit in thestated range. Where the stated range includes one or both of the limits,ranges excluding either or both of those included limits are alsoincluded.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural referents unless the context clearly dictatesotherwise. Thus, for example, reference to “a process” includes aplurality of such processes and reference to “the electrode” includesreference to one or more electrodes and equivalents thereof known tothose skilled in the art, and so forth.

Also, the words “comprise,” “comprising,” “include,” “including,” and“includes” when used in this specification and in the following claimsare intended to specify the presence of stated features, integers,components, or steps, but they do not preclude the presence or additionof one or more other features, integers, components, steps, acts, orgroups.

What is claimed is:
 1. An aqueous binder composition comprising: acarbohydrate; a sequestrant for one or more multivalent ions, whereinthe sequestrant reduces a precipitation rate for the multivalent ionsfrom the aqueous binder composition; and a polymerization catalyst. 2.The aqueous binder composition of claim 1, wherein the sequestrantcomprises a polycarboxylic acid compound.
 3. The aqueous bindercomposition of claim 1, wherein the polycarboxylic acid compoundcomprises at least three carboxylic acid groups.
 4. The aqueous bindercomposition of claim 1, wherein the sequestrant comprisesethylenediaminetetraacetic acid (EDTA).
 5. The aqueous bindercomposition of claim 1, wherein the sequestrant comprises citric acid.6. The aqueous binder composition of claim 1, wherein the sequestrantcomprises a polyacrylic acid compound or a salt of a polyacrylic acidcompound.
 7. The aqueous binder composition of claim 1, wherein thesequestrant comprises a polyphosphonic acid compound or a polyphosphoricacid compound.
 8. The aqueous binder composition of claim 7, wherein thesequestrant comprises at least three phosphonic acid groups.
 9. Theaqueous binder composition of claim 7, wherein the sequestrant comprisesethylenediaminetetramethylenephosphonic acid.
 10. The aqueous bindercomposition of claim 1, wherein the one or more multivalent ions areselected from the group consisting of calcium ions, magnesium ions,barium ions, aluminum ions, and iron ions.
 11. The aqueous bindercomposition of claim 1, wherein the polymerization catalyst is selectedfrom the group consisting of a Lewis acid, a protic acid, and a latentacid.
 12. The aqueous binder composition of claim 11, wherein the Lewisacid is selected from the group consisting of aluminum sulfate, ferricsulfate, aluminum chloride, ferric chloride, aluminum phosphate, andferric phosphate.
 13. The aqueous binder composition of claim 11,wherein the protic acid is selected from the group consisting ofsulfuric acid, phosphoric acid, hydrochloric acid, nitric acid, toluenesulfonic acid, methane sulfonic acid, and a carboxylic acid.
 14. Theaqueous binder composition of claim 11, wherein the latent acid isselected from the group consisting of ammonium sulfate, ammoniumhydrogen sulfate, monoammonium phosphate, diammonium phosphate, ammoniumchloride, and ammonium nitrate.
 15. The aqueous binder composition ofclaim 1, wherein the polymerization catalyst is an organo-metallic saltselected from the group consisting of an organo-titanate salt, anorgano-zirconate salt, and organo-tin salt, and an organo-aluminum salt.16. The aqueous binder composition of claim 1, wherein the carbohydrateis a reducing sugar.
 17. The aqueous binder composition of claim 1,wherein the binder composition further comprises a reaction product of aurea compound and an aldehyde-containing compound.
 18. The aqueousbinder composition of claim 17, wherein the urea compound has theformula R₁R₂N—CO—NR₃R₄, where R₁, R₂, R₃, and R₄ are independentlyselected from the group consisting of H, an alkyl group, an aromaticgroup, and an alkoxy group.
 19. The aqueous binder composition of claim18, wherein the urea compound comprises H₂N—CO—NH₂.
 20. The aqueousbinder composition of claim 17, wherein the aldehyde-containing compoundis selected from the group consisting of acetaldehyde, butyraldehyde,acrolein, furfural, glyoxal, gluteraldehyde, and polyfurfural.
 21. Theaqueous binder composition of claim 20, wherein the aldehyde-containingcompound is glyoxal.
 22. The aqueous binder composition of claim 1,wherein the binder composition further comprises a polyacrylic acidcompound.
 23. The aqueous binder composition of claim 22, wherein thebinder composition further comprises an alkanol amine.
 24. The aqueousbinder composition of claim 23, wherein the alkanol amine is triethanolamine.
 25. The aqueous binder composition of claim 22, wherein thebinder composition further comprises sodium hypophosphite.
 26. Thecomposition of claim 1, wherein the sequestrant is present at aconcentration of between about 0.1 wt. % and about 2 wt % of the aqueousbinder composition.
 27. The composition of claim 1, wherein thesequestrant is present at a concentration of below about 1 wt. % of theaqueous binder composition.
 28. The composition of claim 1, wherein thesequestrant comprises a salt of a polyacrylic acid compound.
 29. Thecomposition of claim 1, wherein the sequestrant consists of apolyacrylic acid, and the composition does not comprise othersequestrants.
 30. The composition of claim 1, wherein the sequestrantcomprises citric acid.
 31. The composition of claim 1, wherein thesequestrant comprises styrene malic anhydride.
 32. The composition ofclaim 1, wherein the sequestrant comprises five or more carboxylic acidgroups.